The invention relates to a thermostat which preferably regulates a bypass of a cooler. Furthermore, the invention relates to a component of an oil circuit, it being, in particular, the oil circuit of a vehicle. The thermostat also preferably serves to regulate a bypass of an oil cooler of the vehicle.
It is known from the prior art that internal combustion engines have an oil circuit, in order to make reliable and low-consumption operation of the internal combustion engine possible. The oil circuit usually also includes an oil cooler which cools the circulating oil with the aid of a cooling liquid, which cooling liquid is provided for cooling the internal combustion engine.
The cooling liquid usually heats up more rapidly than the oil during the warming up operation of the engine. Warming of the oil by way of the cooling liquid is therefore possible during warm up. In order for it to be possible to lower the pressure loss in the system, a constant bypass is provided.
However, the constant bypass can neither make the warming up optimum nor can the complete potential of the oil cooler be exploited in the cooling output case, since the oil is never guided completely via the oil cooler. Furthermore, the temperature of the oil is likewise coupled in a pronounced manner to the temperature of the cooling liquid. In particular during dynamic driving operation, that is to say frequent changing from operation under load of the internal combustion engine into an overrun mode, this can lead to overcooling of the oil, as a result of which the friction within the internal combustion engine increases and the fuel consumption rises.
It is therefore an object of the invention to eliminate these disadvantages. In particular, it is an object of the invention to provide components which permit secure and reliable regulation of the temperature of a circulating fluid, while being simple and inexpensive to produce and operating with low-maintenance.
This and other objects are achieved by a thermostat including a carrier element which can be anchored in a housing, and a valve element which can be moved relative to the carrier element. The valve element bears against the carrier element in a first position, as a result of which a duct within the housing can be closed, and does not bear against the carrier element in a second position which is different than the first position, as a result of which the duct can be opened. The thermostat includes a wax element which is arranged on the carrier element, is connected mechanically to the valve element and is set up to generate a stroke in the case of a temperature change, by way of which stroke the valve element can be moved.
According to an embodiment of the invention, a thermostat includes a carrier element, it being possible for the carrier element to be anchored in a housing. It is possible in this way, in particular, that the carrier element of the thermostat is attached in a bypass of a cooler, preferably an oil cooler. Furthermore, the thermostat includes a valve element which can be moved relative to the carrier element. It is provided here according to the invention that the valve element can be transferred into a first position, in which the valve element bears against the carrier element. A duct, preferably the bypass, can be closed by way of the valve element bearing against the carrier element. It is likewise provided according to the invention that there is a second position of the valve element, which second position differs from the first position and in which the duct can be opened. To this end, the valve element no longer bears against the carrier element in the second position.
Furthermore, the thermostat includes a wax element which is set up to generate a stroke in the case of a temperature change. In particular, the stroke can be produced by way of expansion or contraction of the wax element. The wax element is arranged on the carrier element and is connected mechanically to the valve element. The wax element therefore transfers the stroke to the valve element, as a result of which a relative movement is produced between the valve element and the carrier element.
In one preferred embodiment, the thermostat has a first elastic element. The first elastic element exerts a force on the valve element, by way of which the valve element is forced into the first position, in particular when the valve element is not situated in the first position. It is provided as an alternative or in addition that the valve element is pressed against the carrier element by way of the force of the first elastic element, in particular when the valve element is situated in the first position. Sealing of the duct can preferably be ensured by way of the valve element being pressed onto the carrier element.
It is particularly preferably provided that the first elastic element is set up in such a way that a predefined pressure on the valve element moves the valve element out of the first position. The duct can therefore be opened by way of the predefined pressure. It is advantageously made possible in this way that, in the case of an excessively high pressure, a fluid can escape into the duct, with the result that the thermostat can also be used as a pressure relief valve.
The valve element is advantageously constructed such that it has a first convex surface. The first convex surface preferably seals the first opening of the carrier element when the valve element is situated in the first position. The sealing of the first opening preferably also means closure of the duct.
In a further preferred embodiment of the thermostat, the valve element can be moved linearly. It is preferably provided here that the valve element can be moved linearly away from the carrier element and can be moved linearly toward the carrier element. In this way, in particular, a linear stroke of the wax element can be converted directly into a linear movement of the valve element.
Moreover, it is preferably provided that the valve element bears against the carrier element and/or against the housing in a third position and thus closes the duct. The third position is different from the first and second positions. The transfer of the valve element into the third position preferably always takes place via the second position, with the result that a transfer of the valve element from the first position into the third position and vice versa while bypassing the second position is not possible.
The valve element advantageously has a second convex surface which seals a second opening of the carrier element and/or of the housing in the third position. The second surface is preferably of identical configuration to the first surface.
In one preferred embodiment, the valve element can be moved linearly from the first position into the third position, the second position being any intermediate position between the first and the third position. A linear stroke of the wax element is therefore preferably converted into a linear movement of the valve element, the duct first of all being opened and subsequently being closed again by way of the valve element as the stroke increases.
Moreover, it is preferably provided that the thermostat has a second elastic element. The second elastic element is arranged between the carrier element and the wax element and serves particularly preferably as a compensation element. It is therefore possible that a stroke of the wax element brings about a movement of the valve element and, as an alternative or in addition, a contraction or expansion of the second elastic element. It is therefore possible, in particular, that a stroke of the wax element can be carried out even when the valve element can no longer be moved, which occurs, in particular, when the valve element is situated in the third position.
Furthermore, the invention relates to a component of an oil circuit, in particular an oil circuit in a vehicle. The component according to the invention includes a thermostat as described above and a housing, in which the thermostat is arranged. The housing has an oil inlet and a first oil outlet, the wax element being arranged in such a way that oil which flows from the oil inlet to the first oil outlet washes around the wax element. Furthermore, a second oil outlet can be opened and closed by way of the valve element, the second oil outlet forming the start of the duct. This means that the thermostat can be used to control, within the component, whether oil which enters through the oil inlet is to be guided through the first oil outlet or, preferably, through the second oil outlet.
The component according to the invention is preferably configured in such a way that the first oil outlet is connected to an oil cooler and the duct forms a bypass of the oil cooler. The oil can therefore either pass through the first oil outlet into the oil cooler or can be guided past the oil cooler through the second oil outlet. It is possible to regulate the temperature of the oil in this way.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of one or more preferred embodiments when considered in conjunction with the accompanying drawings.